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Short Summary
Main recommendation: To finish a basement bathroom with rough-in plumbing, cut the drain stubs flush with the concrete, install the toilet flange at the correct height before flooring, and build the shower using the Schluter Kerdi-Board waterproofing system with a new Schluter 90-degree drain, so the room can be finished without re-routing the plumbing or opening the concrete. The video demonstrates the shower-pan build from start to finish, along with toilet flange installation.
Key Points
- Set the toilet flange flush with the concrete before flooring goes in, so the toilet sits at the correct height and seals without leaks.
- Use the Schluter drain's built-in 90-degree turn so the shower drain can connect to the existing stub wherever it sits, avoiding relocation of plumbing.
- The shower is built as a waterproofing system rather than a water-diversion shower, meaning it doesn't rely on a steep slope to direct water.
- The Schluter system uses half-inch polystyrene board fixed with clips and washers instead of screws, providing a rigid, tileable wall with a cloth membrane for waterproofing.
Details Worth Noting
- Concrete instructions:
- Cut the toilet stack (usually a 3-inch pipe, though a 2-inch pipe is possible) exactly flush with the concrete using a flexible ABS saw.
- Install the toilet flange by first grinding a few lines down the inside of the flange to thin the plastic, since it is a tight fit inside the pipe once buried in cement.
- Solvent-glue the inside of the pipe and the fitting, then set the flange so the two bolt slots sit at nine and three o'clock. Push it straight down and stuff a coffee cup in the opening to keep gases out while working.
- For the shower, cut the drain pipe leaving about 1/2 to 3/4 inch of stub so a fitting can attach, then install the Schluter 90-degree drain with a slight slope toward the outlet.
- Fill voids around the plumbing with sand mix, which flows into gaps, then build a slope so water (or the mix) runs toward the drain, and about 1/2 inch of build-up at the four corners.
- Let the sand mix set overnight, then install the Schluter cloth membrane with thin-set, embedding it in the thin-set and sealing corners with the cloth tape.
- Finish by installing tile over the membrane.
- The sand mix used is an inexpensive hardware-store product (about $67, per the speaker, for the bag used); the speaker notes that dry pack is a more traditional alternative but is harder to find.
- Schluter products mentioned include the Kerdi-Board system, the 90-degree drain, the curb, cloth tape, pre-sloped pan membrane, and inside and outside corner pieces.
- The speaker notes that smaller tile can make it hard to fit the last wall piece over the clips, so plan layout accordingly.
- The speaker cautions that the process takes planning time because the sand mix needs to set overnight.
Bottom Line
A rough-in basement bath can be finished without opening the concrete by sizing the toilet flange and drain stubs correctly and using a Schluter waterproofing system, which is the key to a finished shower without reworking existing plumbing.
